Not enough speed with Norma MRP

M

mimile

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Good morning,
I bought some Norma MRP and loaded a 270 win 150 grain Nosler Partition up to their max loads. They list a muzzle velocity of 3000 fps with max load which they tested with a 24 inch barrel.
My rifle is a Sako A7 22,4 in barrel. So I was expecting to get a muzzle velocity of at least 2920. What I got was only 2750. What is going on?
 
Who is "they"?
Just checked the books and 2900 looks like max with 24" barrels.
What was the accuracy? and at what distance.
Velocities out of test barrels are generally optimistic.
What were the velocities on the work up loads and are you at max for your rifle?
 
It\s quite common for actual velocities to fall up 100-150fps short of the velocities listed in manuals. All chambers and barrels vary, and most factory chambers are on the generous side.
 
You may, in fact, not be at a maximum load for your barrel.
My 270 digests 62 grains of MRP behind the 130, 61 behind the 140, and 60 behind the 150.
My rifle is a Vanguard with a 24" barrel, and I clock just shy of 3000 with the 150.
Always work up carefully!! Dave.
 
horseman2 said:
Who is "they"?
Just checked the books and 2900 looks like max with 24" barrels.
What was the accuracy? and at what distance.
Velocities out of test barrels are generally optimistic.
What were the velocities on the work up loads and are you at max for your rifle?
Click to expand...

horsemans2,
Thank you for replying. I took the data from the Norma manual. They list 3000 fps for a 24 inch barrel. I was shooting at 100 yards. The accuracy was great around 0.80 moa at 2750 fps. Between 55.2 grain and 56.7 the speed stayed roughly the same. All shots were very close.
 
Eagleye said:
You may, in fact, not be at a maximum load for your barrel.
My 270 digests 62 grains of MRP behind the 130, 61 behind the 140, and 60 behind the 150.
My rifle is a Vanguard with a 24" barrel, and I clock just shy of 3000 with the 150.
Always work up carefully!! Dave.
Click to expand...

Thanks Dave. That's very precious information.
 
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